Variations in paint thickness in a painting often enhance the painting's appearance. For example, paint thickness is an important aspect of impasto paintings. Impasto is a technique where paint is laid very thickly in places to provide intriguing visual effects. Impasto paintings often show the shape of brushes and strokes, interleaving between paint and canvas fiber, and the layered mixture of paint colors. Techniques used to render impasto paintings on computing devices generally provide an inadequate, unrealistic, and unintuitive viewer experience. Two dimensional (2D) representations appear flat and do not allow the user to appreciate the thickness variations in the paintings. Attempts to instead represent impasto paintings using three dimensional (3D) shapes also do not provide an adequate user experience. With real artwork, the user can change his viewing position or rotate the artwork to observer shadow and other effects caused by the depth variations to get a spatial appreciation of the depth variations in the painting. In contrast, computer renderings of 3D shapes representing impasto paintings are presented in virtual 3D environments that are complicated and cumbersome to manipulate. Such an environment can include a 3D model in which the artwork is displayed, and a light source is defined, and a viewer position is defined. To change his viewing perspective, the user must manually interact with the 3D model using a computer input devices such as a mouse, pen, or trackpad to specify a new position for the artwork or viewer position. This is cumbersome, difficult, and not intuitive for many users. As a result, the user does not have the same real-world, intuitive experience of moving or rotating the artwork to change his or her viewing perspective to appreciate the artwork's depth.